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Pull an EC2 console log using the AWS CLI api and jq

AWS provides a REST Api to everything they offer, and returns the results in Json format. If you have a server in a private network in a VPC, you might want to get the logs to see what happened at boot time, and the aws cli gives you a simple way of doing that:

aws ec2 get-console-output --instance-id {i-xxxxxxxx}

This is great for many things, but the data from a server console log isn't one of them. You get the log as a giant string in the 'Output' key:

{     "InstanceId": "i-005a7e6e8ae....",      "Output": "[    0.000000] Initializing cgroup subsys cpuset\r\n[    0.000000] Initializing cgroup subsys cpu\r\n[    0.000000] Initializing cgroup subsys cpuacct\r\n[    0.000000] Linux version 4.1.13-19.30.amzn1.x86_64 (mockbuild@gobi-build-64011) (gcc version 4.8.3 20140911 (Red Hat 4.8.3-9) (GCC) ) #1 SMP Fri Dec 11 03:42:10 UTC 2015\r\n[    0.000000] Command line: root=LABEL=/ console=ttyS0 \r\n[    0.000000] e820: BIOS-provided physical RAM map:\r\n[    0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009dfff] usable\r\n[    0.000000] BIOS-e820: [mem 0x000000000009e000-0x000000000009ffff] reserved\r\n[    0.000000] BIOS-e820: [mem 0x00000000000e0000-0x00000000000fffff] reserved\r\n[    0.000000] BIOS-e820: [mem 0x0000000000100000-0x000000003fffffff] usable\r\n[    0.000000] BIOS-e820: [mem 0x00000000fc000000-0x00000000ffffffff] reserved\r\n[    0.000000] NX (Execute Disable) protection: active\r\n[    0.000000] SMBIOS 2.4 present.\r\n[    0.000000] Hypervisor detected:

This is where the great json processor jq can be used, both to extract just the output, and to convert the encoded newline characters back into actual newlines using the -r flag.

aws ec2 get-console-output --instance-id i-005a7e6e8aeae06 | jq -r '.Output' 

And we get the logs, just as if we were sitting at the console:

[    0.000000] Initializing cgroup subsys cpuset [    0.000000] Initializing cgroup subsys cpu [    0.000000] Initializing cgroup subsys cpuacct [    0.000000] Linux version 4.1.13-19.30.amzn1.x86_64 (mockbuild@gobi-build-64011) (gcc version 4.8.3 20140911 (Red Hat 4.8.3-9) (GCC) ) #1 SMP Fri Dec 11 03:42:10 UTC 2015 [    0.000000] Command line: root=LABEL=/ console=ttyS0  [    0.000000] e820: BIOS-provided physical RAM map: [    0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009dfff] usable [    0.000000] BIOS-e820: [mem 0x000000000009e000-0x000000000009ffff] reserved [    0.000000] BIOS-e820: [mem 0x00000000000e0000-0x00000000000fffff] reserved [    0.000000] BIOS-e820: [mem 0x0000000000100000-0x000000003fffffff] usable [    0.000000] BIOS-e820: [mem 0x00000000fc000000-0x00000000ffffffff] reserved [    0.000000] NX (Execute Disable) protection: active [    0.000000] SMBIOS 2.4 present. [    0.000000] Hypervisor detected: Xen [    0.000000] Xen version 4.2. [    0.000000] Netfront and the Xen platform PCI driver have been compiled for this kernel: unplug emulated NICs. [    0.000000] Blkfront and the Xen platform PCI driver have been compiled for this kernel: unplug emulated disks. [    0.000000] You might have to change the root device [    0.000000] from /dev/hd[a-d] to /dev/xvd[a-d]

As it turns out, there is a far easier solution to this problem, pointed out in a comment to this post. You can just use an --output text option:

aws ec2 get-console-output --output text --instance-id i-005a7e6e8aeae06 


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margaret on :

*jq is great and all but it seems '--output text' would be the way to go.

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